Objects of different steel materials or iron-based alloy materials are usually assembled by brazing or soldering with Nickel-based or Copper-based brazing materials. Hereinafter the term brazing is used, but it should be understood that the term also comprises soldering. Brazing is a process for joining parts of metals, but brazing can also be used for sealing objects or coating objects. The brazing temperature is below the original solidus temperature of the base material. During brazing, the brazing material is completely or partly melted.
Traditional brazing of iron-based materials is performed using Nickel-based or Copper-based brazing materials, and these brazing materials can cause corrosion due to, for example, differences in electrode potential. The corrosion problem will be enhanced when the brazed object is exposed to a chemically aggressive environment. The use of Nickel-based or Copper-based brazing material can also be limited in a number of food applications due to regulations.
One problem is the melting point of the coating or brazing materials, which are highly alloyed. When selecting a brazing material or a coating material, considerations are based on the solidus or liquidus temperatures of the alloy and the base material. Lately, iron-based brazing materials have been developed for brazing objects of traditional stainless steel. One problem which can occur happens when the base material of an object is a high-alloyed iron-based material, since these lately developed iron-based brazing materials will have a different electrode potential compared to the high-alloyed iron-based material. Differences in electrode potential between the brazed areas and the base material of the object can cause corrosion problems when the high-alloyed steel objects are used in certain environments and applications. The high-alloyed steels have been developed to obtain improved properties for applications in environments which are corrosive, chemically aggressive etc. Therefore, there is a need that the brazing material, when brazing highly alloyed steels, has similar properties such as corrosion resistance as the high alloyed base material, otherwise the brazing material may limit the properties of the brazed product.
High-alloyed iron-based materials are today mainly welded, since the difference in properties between the present brazing materials like for instance Cu—, Ni, and Fe based brazing materials are too wide. The welding technique is costly and time consuming and thus not desirable because the welding normally results in significant stresses in the produced product.